Selective a.c.-d.c. system.



J. F. TRITLE.

SELECTIVE A. (1- D. G. SYSTEM. APPLIOATION FILED JAN. 1B, 1908.

QSQQTK'G Patented Sept. 28, 1909.

Wifnesses Invenon M b %ZZZ E?T/ifilg y M ACEY.

SCHENEC'I'ADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC JOHN F. TBI'I'LE, F

n ce

COMPANY, A CORPORATION 0F NEKV YORK.

SELECTIVE A.C.-D.C. SYSTEM.

Specification of Letters Patent. Patented Sept. 28, 1909- Application filed January 18, 1908. Serial No. 411,453.

To all whom it may concern:

Be it known that 1, JOHN F. TRITLE, a citizen of the United States, residing at Schenectady, county otSchencctady, State of New York, have invented certain new and useful Improvements in Selective A.C.-D.C. Systems, of which the following is a specification.

In electrically driven cars intended for operation either on alternating or direct current, usually high potential alternating currcnt' and low. potential direct current, the

change 1 0111 one to the other being ordinarily made while the car is moving, it is customar to provide a system of selective switches 'auged to automatically connect the curren collecting device to the proper circuits oftthe car for either alternating or direct current operation. Si ch a system of selective switches is shown in the patent to Frank and Ievea r, No. 854,730, dated May 28, I

1907, Control of electric cars. The arrangement there shown consists of a small stepdown. transformer having its primary connected to the power circuit, the actuating coil of the AC. switch 'being connected across the secondary of said transformer,

and the actuating ,coil of thc' DC. switch transformer has had time to build up may operate the D.G. switch. Such an occurrence is, of course, highly objectionable, and

it is an object of my invention to provide means for absolutely and certainly prevent ing the DC. switch from operating when the car enters, or while it ison an alternating current section.

In order to overcome the above mentioned objection, my invention consists in provid ing, in a system of the kind above men-. tioncd, a contact on the IlCl switch arranged to short-circuit a portion of the actuating coil of said switch when said switchv is in its open position. The eflect of. this short-circuiting of a portion of the actuating coil of the D.C. switch is to cause this coil to operate as a transformer with its secondary short-circuited, the result of which, if the division of the coil is properly made, is to reduce the magnetic flux threading the coil to practically zero. The DC. switch is thus prevented from operating 011* alternatiug current.

My invention further contemplates the use of a contact closed by the closing of the AC. switch for completing a shunt circuit from the primary of the transformer to ground around the actuating coil of the DC.

' switch.

My invention will best be understood from the following description taken in connection with the accompanying drawing, in which I have shown diagrammatically one form in which it ma be embodied.

I deem it unnecessary to illustrate any-systeiu of motor control, as it is obvious that my invention is not limited in its application to any particular control system. It may,

1 however, be stated that, as illustrated, my

and the potential of the direct current section being relatively low, for evample, 600

volts.

The usual kicking coil and lightning artional manner at A.

The main switch whjchi-s intended toclose only on alternating current operation is indicated at b, and the main switch which closes only on direct current operation is shown at S. These switches S and may be of any suitable design.

at small step-down transformer, represented at E, is shown with its primaryconnected between trolley and ground. The actuating coil 1 of the AC. switch S is conneeted across the secondary of the trans former E, and the actuating coil 2 of the 13.0. switch S is connected in series with the primary of the transformer E. This coil 2 is connected permz'n'iently to ground through the non-inductive resistance 3. An. in-

lei-mediate point, such as a, on the coil its also connected to ground through a contact 5, closed when the switch {'5 is in its open position but opened when said switch closes. A contact 6, closed by the All. switch S in closing, connects the primary of the transformer E directly to ground, thereby shunting the coil 2 of the switch S The operation of my selective system is as follows,--Suppose the switches S and S in their open position, as illustrated in the drawing: lit" the current -collecting device engages with a supply coi'iductor furnishing alternating current at high potential,cur-

rent will flow from the line, through the primary of the transformer E, the upper part of the coil 2 to the point L, and thence to ground through the contact 5. The first rush of current which occurs before the counter E. M. F. of the transformer E has had time to build up, might be sufficient to close the-11G. switch S were it not for the fact that the lower part of the coil Qlocing shoii't-circuited causes the coil 2 to act as a transformer having its secondary short circuited, and therefore the magnetic aux passing through it to be practically zero. The switch S, will, therefore, not close on alternating current. The All. switch will, however, he closed by the energization of its coil 1. from the secondary of the transformer E. The switch S in closing closes the contact- (5 and shunts the actuating 'coil 2. of the switch S. If the current collecting device T engages a supply conductor fur- -nishing direct current, current will flow through the primary of the transformer E and the impel. part of the coil 2 of the switch S 'througl'i the contact 5 to ground. The magnetization produced by the upper.

part of the coil 2 will he sutlicient to close theswitch S, which. in closing opens the "f contact 5 and forces the current to flow "through the whole of the coil 2 and the resistance o to ground. The switch S is,

'tlun'clorc, held closed lay current which rester are indicated in a well known c0nvenf passes througlrthe whole of the coil .2 which currentis reduced to a safe value to avoid heating by the resistance 3. The switchS, of course, will be unaffected by directcun rent.

' It is not my intention to limitmyself to the particular arrangement of devices shown. I. aim to cover in the following claims all modifications which are within the scope" of my invention.

What I claim as new, and desire to secure 1) r 1 l. A selective A.C.-D.C.- system for elec tric cars comprising energy transformin means the primary of which is connecte to the power circuit, an AC. switch, an actuating coil. therefor connectcd to the any of said transforming means, a D.C. switch, an actuating coil therefor connected to the power circuit through the primary of said transformingmeans, and. contacts con trolled by said 1).U. switch arranged to short circuit a portion of the actuating coil of said switch when said switch is in its open position.

2. A selective A .C.-D.G system for eleclrlc cars comprising energy transforming means the primary of which is connected to the power circuit, an AL). switch, anactuating coil there-for connected to thesecondary of said transforming means, a DLC.

second- 3 switch, an actuating coil therefor connected to the power circuit through the primary of said transforming means, and contacts closed by said Ail. switch in closingfor completing a shunt circuit around the actuating coil of the 11C. switch.

'3. A selective A.C.-D.G. system forel'cl'ric cars comprisinga transformer having its primary connected to .the power circuit, an All; switch, an actuating coil thereforconnectcd across the secondary of said transformer, a D13. switch, an actuating coil therefor in series with the primary of said transformer, and contacts controlled by said 110. switch arranged to short-circuit a portion of the actuating coil of said switch when said' switch is in its open position.

t. A selective A.()'.-D.C. system for electrio cars comprising a transformer having its primary connected to the power circuit, an All. switch, an actuating coil-therefor connected across the secondary of said transformer, a D13. switch, an actuating coil therefor in series with the primary of said tigulsformc and contacts closed by. said All.

switch in closing for completing a shunt circuit from the primary of said transformer around the actuating coil of the 11C. switch.

5. A selective i\.(l. -D.G. system for electric cars comprising a transformer having its )rimar connected to the )ower circuit an All. switch, an actuatin coil therefor connected across the second hry of said transformer, a DC. switch, an actuating coil there-for in series with the primary of said transformer, contacts controlled by Said D1). switch arranged to short circuit a portion of the actuating coil of said switch when said switch is in its OPBH position, and contacts controlled by said All. switch arranged when the All. svitoh closes to complete a shunt circuit from the primary of 'said trans- In witness whereof, I have hereunto set my hand this 16th day of January, 1908.

JOHN F. TRIPLE W itncsscs llnmiusim B. HULL, HELEN Onrono. 

